250,000 volt transformer

• To: tesla-at-pupman-dot-com
• Subject: 250,000 volt transformer
• From: "Eric Davidson" <edavidson-at-icva.gov> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
• Date: Fri, 24 Mar 2000 12:21:55 -0700
• Approved: twftesla-at-uswest-dot-net
• Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

Hi all,
 
I ve been following this whole discussion on the 250kV potential transformer,
so I just had to add my $0.02.  The "primary" of this transformer consists of a
series string of film capacitors immersed in oil which produces a capacitive
voltage divider (CVD).  The high voltage, in this case 250kV, is applied to the
"top" of the string of caps.  The "bottom" of the string of caps is grounded. 
The capacitor string is tapped at about the 10% (from ground) region to give a
potential of about 25kV.  This voltage is applied to the primary winding of the
actual core and coil part of the potential transformer which steps the 25kV
from the CVD down to 120 volts or whatever, to run the measuring device or
meter.   If you apply the low voltage (120 V) to the output terminals, the
potential on the high voltage terminal will be the voltage determined by the
turns ratio of the core and coil part of the device only, NOT 250kV.  Yes, the
voltage may be a bit different due to resonance effects, but not much.  A
capacitive divider,  like its resistive counterpart, has no transformer action
and will not raise the voltage, unlike a an autotransformer or, if you will, an
"inductive voltage divider".  If I owned this device I would shag out the core
and coil and junk the rest, well, maybe I'd save the huge insulator for a
conversation piece.  Hope this helps.  Coil safely.
 
Eric
<mailto:edavidson-at-icva.gov>edavidson-at-icva.gov
 

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